There has been disclosed an inkjet printer which includes a detachable main tank, a sub tank which stores ink supplied from the installed main tank, and an image recording unit which ejects the ink stored in the sub tank to record an image. The inkjet printer is configured such that the inner spaces of the main tank and the sub tank are open to the air. Therefore, when the main tank is installed in the inkjet printer, the ink moves such that the liquid levels of the ink of the main tank and the sub tank become flush with each other by a difference between the water head of the inner space of the main tank and the water head of the inner space of the sub tank (hereinafter, referred to as “water head difference”).